Thermal Conductivity Of Toluene Research Articles

Experimental measurements of thermal conductivity of hydrocarbon fuels by a steady and kinetic method

A steady and kinematic thermal conductivity measurement method is proposed for the round tube flow in laminar regime under constant heat flux condition. And this method is based on the fact that heat transfer coefficient depends only on thermal conductivity λ and inner diameter and is independent of V, ρ, and Cp in laminar flow with fully developed temperature and velocity profile. This independence results from the fact that the energy transport is purely molecular conduction problem under these conditions. The uncertainty of the measurement is within ± 3.0 % (coverage factor k = 2) according to the uncertainty analysis. For validation, the thermal conductivity of toluene and ethanol was measured at the temperature range of (288–372) K. And the validation tests show that the relative deviation of measured thermal conductivity from standard data is within an error band of 2 %. Using this method, thermal conductivity of a typical hydrocarbon aviation fuel RP-3 was measured.

Thermal Conductivity Measurement of TBAB Hydrate by the Transient Hot-Wire Using Parylene-Coated Probe

Semiclathrate hydrate consists of cage structures composed of water molecules and ionic large guest molecules, which distinguish semiclathrate hydrate from normal clathrate hydrate. Semiclathrate hydrate is stable under atmospheric pressure condition and at near room temperature. This is the reason semiclathrate hydrate is expected to be used in various novel technologies, for example use as a cool-energy storage agent and gas separator. However, there is little knowledge about thermophysical properties of semiclathrate hydrate. Up to the present, few experimental data on its thermal conductivity have been reported. Thermal conductivity is necessary for the evaluation of industrial formation process of semiclathrate hydrate and heat transfer performance of semiclathrate hydrate used as cool-energy storage agent. The present paper reports measurements of the thermal conductivity of Tetra Butyl Ammonium Bromide (TBAB) hydrate by the transient hot-wire technique using a newly developed Parylene-coated probe, in which a metallic wire is coated with a thin electrical insulation layer formed by a chemical vapor deposition of poly-para-xylyene polymer. In order to confirm the reliability of the probe, we have performed check measurements on the thermal conductivity of toluene and water. We have measured the thermal conductivity of TBAB hydrate in the temperature range from 193 to 282 K with the uncertainty of ±2 %. It is found that the thermal conductivity of TBAB hydrate is less than 17 % of that of ice with almost no temperature dependence and its absolute value is lower than that of normal clathrate hydrate such as methane hydrate.

A simple method for large scale synthesis of highly monodisperse gold nanoparticles atroom temperature and their electron relaxation properties

Here we demonstrate a simple method for large scale preparation ofmonodisperse gold nanoparticles by simple mixing of chloroauricacid (HAuCl4) with oleylamine (OA) at room temperature. The as-prepared gold nanoparticles havehigh monodispersity with an average diameter of 13 nm and can self-organize intotwo-dimensional (2D) hexagonal close-packed arrays. The size of the gold nanoparticles canbe experimentally controlled. The capping agent, oleylamine, can be easily replaced withother capping agents such as thiol groups for further functionalization. The electronrelaxation dynamics of these gold nanoparticles in toluene was studied by femtosecondpump–probe measurements, in comparison with the citrate-stabilized gold nanoparticles inwater. The phonon–phonon relaxation time of gold nanoparticles in toluene is slower thanthat of citrate-capped gold nanoparticles in water, due to the lower thermal conductivity oftoluene than water. The electron–phonon relaxation of the gold nanoparticlesin toluene was found to display weaker pump energy dependence, compared tothat of citrate-capped gold nanoparticles in water. The different electron–phononrelaxation dynamics is ascribed to the extra vibrational states provided by gold-NH2, which serves as an extra nonradiative relaxation pathway for the e–ph relaxation inoleylamine-capped gold nanoparticles in toluene.

Thermal diffusivity and thermal conductivity of toluene by photon correlation spectroscopy: A test of the accuracy of the method

Absolute measurements of the thermal diffusivity of liquid toluene were performed by photon correlation spectroscopy between 393 and 523 K near the saturation line. The experimental method is based on a time-resolved analysis of the laser light scattered from local equilibrium fluctuations in a transparent sample. enabling us to obtain the thermal diffusivity in macroscopic thermodynamic equilibrium. The experimental results are compared with previous data obtained with the same method, with the transient-hot-wire technique. and also with calculated values of thermal dilhusivity from reference data for thermal conductivity, heat capacity, and density. They demonstrate an agreement of 2.5%. which is within the uncertainty of the reference data.

The thermal conductivity of toluene and water

A new instrument is presented to measure the thermal conductivity of polar and electrically conducting liquids based on the transient coated hot-wire method. The performance of the apparatus has been assessed with toluene and water, which are recognized as standard reference materials for nonpolar and polar fluids, respectively. New results are reported fort the thermal conductivity of these liquids between 298 and 370 K and at pressures slightly above the saturation. The results show that the instrument is capable of an accuracy better than ±0.5%, while the precision and reproducibility are better than ±0.3%.

The thermal conductivity of toluene and water

The thermal conductivity of toluene and water

Thermal conductivity of polystyrene above and below the glass transition temperature.

The thermal conductivity of polystyrene is measured in a temperature range of 273 to 513 K by a transient hot-wire method. To confirm the validity of the experimental apparatus and procedure, the thermal conductivity of toluene is also measured in a temperature range of 273 to 323 K for comparison

Measurement of thermal conductivity of liquid fluorocarbons

The thermal conductivity of ten liquid fluorocarbons, R 11, R 12, R 13, R 13B1, R 22, R 113, R 114, R 115, R 114B2, and R 124, was measured in the temperature range from 204–450 K by using the transient hot wire method. Prior to the measurement of the fluorocarbons, the thermal conductivity of toluene as the reference material was measured. The results for toluene agree with the recommended values by Nagasaka and Nagashima within ±1%. The accuracy of the present results for fluorocarbons is estimated to be better than ±1.5%. The results are compared with the equation by Li and Poole. The equation proves to be unsuitable for some fluorocarbons, and modified Li-Poole equations including the number of fluorine atoms are proposed for the three groups of fluorocarbons based on the smoothed values of this work and are compared with the experimental data.

Thermal conductivity of toluene in the temperature range 35–90°C at pressures up to 600 MPa

New, absolute measurements of the thermal conductivity of liquid toluene are reported. The measurements extend over the temperature range 35–90°C and the pressure range 0.8–600 MPa. A new analytic evaluation of the contribution of radiation in an absorbing emitting fluid to the measurement process is presented. This analysis indicates that the thermal conductivity determined in a transient hot-wire instrument is the radiation-free value. As a consequence it is possible to assert that the overall uncertainty in the experimental data is one of ± 0.3%. A comparison of the data with the results of independent measurements by the same technique shows that the various sets of data are consistent within their mutual uncertainty.

Thermal conductivity of fourteen liquids in the temperature range 298?373 K

New experimental data on the thermal conductivity of 14 organic liquids at atmospheric pressure are presented in the temperature range from 25 to 100°C. The liquids measured are five n-alkanes (C6, C7, C8, C10, C12), cyclohexane, six aromatic hydrocarbons (benzene, ethylbenzene, o-, m-, p-xylenes, isopropylbenzene) and two phenyl halides (chloro-, bromobenzenes). The measurements were performed by a transient hot-wire method on a relative basis. The thermal conductivity of toluene, which was selected as a reference liquid, was determined on an absolute basis with another transient apparatus. The precision of the present experimental results is within ±1.2%. The uncertainty of the thermal conductivity values is estimated to be within ±2%; this includes the uncertainty of the values of toluene as the reference liquid. The experimental results for each liquid are represented satisfactorily by a linear equation in temperature. At a reduced temperature T/T c=0.5, thermal conductivity has a simple relation with the molar density for each homologous series of liquids.

Experimental study concerning the contribution of the radiative component to the effective thermal conductivity of toluene

The coaxial-cylinders method was used in an experimental study concerning the contribution of the radiative component to the effective thermal conductivity of toluene. It has been found that this contribution becomes quite significant at high temperatures.

An experimental investigation of the thermal conductivity of toluene by high pressures

An experimental investigation of the thermal conductivity of toluene by high pressures

Experimental study of the thermal conductivity of toluene at high pressures

The experimental apparatus used for determining the thermal conductivity of toluene at temperatures of 0–180°C and pressures of 0.098-49.0 MN/m2 is described, and some of the results are presented. Computing relationships providing an excellent representation of the experimental data are derived.

Experimental investigation of the thermal conductivity of toluene

The procedure of measurements of the thermal conductivity of toluene by the heated filament method is described and the results measured in four measuring cells in the temperature range of 0–130°C are presented. The effect of gap thickness on the heat transfer in liquids is discussed.

Experimental investigation of the thermal conductivity of toluene, biphenyl, and carbon tetrachloride vapor

New experimental data have been obtained on the thermal conductivity of toluene, biphenyl, and carbon tetrachloride vapor. The data obtained are compared with formulas proposed for the thermal conductivity of polyatomic gases and also with the data of recent NBS tables.

A modification of the measuring cell for the investigation of the thermal conductivity of liquids and gases by the hot-wire method

The construction of an instrument for measurements by the absolute hot-wire method is described. The thermal conductivity of toluene, benzene, carbon tetrachloride, and air in the temperature range 20–160° C was measured to an accuracy of 1% Natural convection in the cylindrical gap (δ=0.675 mm) when the measuring cell is vertical occurs when GrPr > 3400.